This invention relates generally to methods and systems for combustion processes, and more particularly to methods for remotely monitoring conditions of a combustion process.
Accurately analyzing internal conditions of a combustion process is an essential task for an operator to better control temperatures of different regions in an environment, such as a furnace or flare, for producing products more efficiently and for saving energy-related costs. Typically, image-capturing devices, such as color cameras, infrared spectrometers, filtered cameras, and the like, are installed in the environment (e.g., in an enclosure) for detecting the temperatures of the environment. Intensities of image pixels received from the devices have a direct relationship with the temperatures of viewed surfaces inside the environment. Similarly, multi-spectral cameras have been used to detect the temperature of a flame and gas species.
Certain methods of video-based technology provide color or intensity images to the operator allowing the operator to manually interpret the state of the combustion process based on the images. An example intensity-temperature calibration and transformation is provided in commonly assigned US 2015/0362372 A1. Another technology performs off-line intensity-temperature calibration and maps each color image to a specific temperature image, thereby providing a two-dimensional (2D) projection of the temperature and/or radiance field. Other technologies, such as laser and acoustic sensing, offer three-dimensional (3D) temperature and/or radiance field estimation at specific locations inside the furnace enclosure. However, a number of required sensors, a related cost, and a complicated installation often make such systems impractical in a large-scale enclosure. Example 3D temperature and/or radiance field estimation systems and methods are provided in commonly assigned U.S. Pat. No. 9,196,032 and U.S. 2015/0355030A1.
The 3D visualization of a combustion operation inside an enclosure in refining and petrochemical industries has been a difficult task. In a furnace, for example, small viewports on a side of the furnace are typically used by furnace operators to look inside the furnace for a visual assessment of the operation. Each viewport typically provides a limited field of view, and thus some internal regions of the furnace are not clearly visible from the side viewport.
Moreover, temperatures of the internal regions of the furnace are extremely high adjacent the viewports, and thus it may be undesirable to stand close to the viewports for the operators. In certain cases, the operators commonly experience heat exhaustion and minor skin burns while standing near the viewports for visual assessment of the combustion process. Due to this exceptionally uncomfortable and undesirable experience of being close to the viewports, the operators often make a hasty interpretation of what has been viewed through the viewports, thereby causing inaccurate assessment of the combustion process.
Another technology for video-based, three-dimensional temperature and/or radiance field estimation applies thermal radiation transfer equations to temperature images. However, this method is inefficient and inaccurate, and does not provide a required resolution and accuracy due to complex, iterative computations required to resolve unknown temperature and radiance fields in the enclosure. Another cause of inaccuracy is poor-quality images due to incorrect or limited controls of the image-capturing devices. Achieving an acceptable accuracy in high resolution and accurate alignment of the images, along with information about a physical structure of the enclosure, are essential. Further, relative positions of the image-capturing devices and imaging areas, such as enclosure walls, often shift their alignments and thus cause significant errors.
Further, in environments such as petrochemical and refinery environments, the process and furnace conditions often change due to upstream conditions, sometimes in an uncontrollable manner. Environment parameters, such as a feed flow, a burner fuel flow, or a furnace draft, can drastically change in a short time period. As a result, the conditions in an environment such as a furnace can change significantly. For example, changes in flame shape can lead to increased production of carbon monoxide (CO) or nitrogen oxide (NOx) gases. Similarly, an increase in flame length can produce flame impingement in the process piping, undesirably changing the conditions for the chemical processes occurring therein. To maintain optimal process conditions and to operate in a desired manner, burner adjustments need to be performed when such conditions occur. However, manual adjustments can be time-consuming and expensive, and further delay current operation during the adjustments. Further, such adjustments are subject to the judgement of the operator, who often does not have the support of various data and measurements related to environmental conditions, thereby causing inaccurate and ineffective adjustments.
Therefore, there is a need for improved methods of analyzing conditions of a combustion process in an environment.